1. Field of the Invention
The present invention relates to a current-perpendicular-to-plane (CPP) tunneling magnetoresistance (TMR) or giant magnetoresistance (GMR) sensor, and more particularly to a CPP TMR or GMR sensor epitaxially grown on a bottom shield.
2. Description of the Related Art
The heart of a computer is a non-volatile storage device that is referred to as a magnetic disk drive. The magnetic disk drive includes a magnetic disk as well as write and read heads. The write and read heads are supported by a slider that is mounted on a suspension arm. When the magnetic disk rotates, an actuator swings the suspension arm to place the write and read heads over selected circular tracks on the surface of the rotating magnetic disk. An air flow generated by the rotation of the magnetic disk causes an air bearing surface (ABS) of the slider to fly at a very low elevation (referred to as the fly height) over the surface of the rotating magnetic disk. The write and read heads write magnetic transitions to and read magnetic transitions from the rotating magnetic disk, respectively. Processing circuitry connected to the write and read and heads then operates according to a computer program to implement writing and reading functions.
The write head includes a coil embedded in an insulation stack that is sandwiched between main and auxiliary poles. The main and auxiliary poles are magnetically coupled at a back gap and are coated with an overcoat. A write current conducted to the coil induces a magnetic flux in the main pole that causes a magnetic field to write the aforementioned magnetic impressions to the rotating magnetic disk.
The read head includes a sensor electrically connected with top and bottom electrodes, but electrically insulated by insulating films from bias stacks at two side regions. A sense current conducted through the top electrode, sensor, and bottom electrode causes changes of resistance in response to external magnetic fields of magnetic transitions from the rotating magnetic disk.
In some cases, the performance of the sensor may be degraded due to temperature increases during sensor processing or manufacturing. To prevent the sensor from this performance degradation, there is a desire to improve the thermal stability of the sensor. Accordingly, what is needed are a sensor and method for providing the sensor with improved thermal stability.